Nasogastric tubes are available in a variety of sizes and materials, the selection for any given patient depending on factors such as the size and age of the patient, the expected duration of the intubation, and the precise purpose for such intubation. In general, nasogastric tubes are commonly available in sizes ranging between 6 to 18 French (2 to 6 millimeters) although even smaller sizes are known. Sizes of 8 to 12 French are often used for adult nasogastric feeding tubes whereas sizes of 5 French or smaller are sometimes used for infant feeding tubes. In contrast to tubes used for aspirating purposes, which are commonly formed of fairly stiff materials such as polyvinyl chloride for resisting collapse under suction, feeding tubes are usually formed of materials that are relatively soft or of low durometer readings such as, for example, silicone rubber.
Copending co-owned application 197,826, filed May 23, 1988, discloses a nasogastric tube holding device having a pair of clamping jaws that are readily adjustable for holding nasogastric tubes of different sizes and durometer values. The clamping jaws are pivotally mounted immediately adjacent the edge of a flexible pad that is adhesively secured over a wearer's nose when the device is in use. The jaws may be securely latched together and are maintained in such latched condition by positive action rather than spring action, but are nevertheless separable when adjustment or release of a nasogastric tube is required. Close proximity of the jaws to the end of the patient's nose, and the relative stiffness of that portion of the pad overlying the ridge of the nose, eliminates or greatly reduces any likelihood of pistoning actions sometimes found in prior art devices. In general, the nasogastric tube holder of the copending application has been found highly effective under a variety of conditions, overcoming the described shortcomings of the prior art, especially when the nasogastric tubes are used for aspiration.
When a nasogastric tube is used for feeding purposes, special problems may be presented. While the relative softness of a feeding tube enhances patient comfort and is desirable for other reasons as well, the ease with which such a tube may be deformed presents the problem of achieving an effective non-slipping clamping action without at the same time unacceptably deforming the tube. If only a gentle clamping force is applied, the holding action may be insufficient to withstand a strong or abrupt pulling force on the tube. Should axial displacement of a tube occur and go unnoticed, further fluids supplied through the tube may place the patient at risk. On the other hand, if the clamping jaws are closed tightly about a soft feeding tube to avoid any possibilities of displacement, the lumen of the tube, depending in part on the size of the tube involved, may become objectionably constricted.
Accordingly, the present invention is concerned with a nasogastric tube holding device that has many of the important advantages of the device disclosed in the aforementioned copending application but is particularly useful with relatively soft nasogastric feeding tubes over a wide range of sizes. Clamping forces may be easily applied to retain feeding tubes as small as 3 French (1 millimeter) or as large as 18 French (6 millimeters) and, even if excessive clamping forces should happen to be applied, lumen occlusion is a practical impossibility. Because of its distinctive multi-plate jaw construction and the beveled edges provided by such plates, the jaw assembly securely holds even a relatively soft feeding tube against slipping movement without the application of extraordinary clamping force.
In addition, the nasogastric tube holding device of this invention is adjustable and releasable with its jaw-latching mechanism exposed above the pivot pin for ready access when adjustment or release of the jaws is desired. Despite such accessibility, the latching mechanism does not project any appreciable distance above the pin so as to obstruct or interfere with the wearer's vision. Further, the latching mechanism is constructed so that, despite its accessibility, release takes place only if certain specific manipulative actions are performed, thereby insuring against inadvertent or unintentional release.
Briefly, the assembly of this invention takes the form of a flexible nose pad adapted for adhesive attachment over a wearer's nose, a mounting pin secured to the pad with its axis generally parallel with the pad and with an end portion projecting from the pad's distal edge, a pair of opposing clamping jaws pivotally supported by the projecting end portion of the pin for movement between open position and a plurality of closed positions, and releasable latching means disposed above the pin for selectively latching the jaws in any of their closed positions. Each of the jaws has a plurality of spaced, parallel clamping plates disposed beneath the pin for clamping and holding a nasogastric tube, particularly a feeding tube, when the jaws are closed. A characteristic of the jaws is that they are engagable with a nasogastric tube from four directions with the lines of contact generally defining a quadrangle of approximately diamond shape, making it impossible as a practical matter to apply clamping forces to even a relatively soft feeding tube that are of sufficient magnitude to occlude the lumen of that tube.
The clamping plates of one jaw are offset in relation to the clamping plates of the other jaw for interdigitation of the plates when the jaws are closed. Therefore, the lines of contact not only extend on four sides of the tube when the tube is viewed in cross section but are also applied at several axially-spaced zones when the tube is viewed in longitudinal section. At least some, and preferably all, of the clamping plates provide beveled contact surfaces terminating in narrow tube-contacting edges that effectively grip the outer surface of a tube for securing that tube against slippage.
The releasable latching means includes two parallel series of ratchet teeth provided by one of the clamping jaws and two flexible latching arms provided by the other jaw. The arms have end portions with latching teeth for engagement with the ratchet teeth for securely holding the clamping jaws in any selected position of adjustment. Since the ratchet teeth of the two series are offset relative to each other, and since the latching teeth of the flexible arms are disposed in side-by-side alignment with each other, only the latching teeth of one of the arms makes latching engagement with the ratchet teeth at any given time. The result is an arrangement which permits close or fine adjustment of the latching mechanism over the full range of tube sizes capable of being clamped by the mechanism.
Other features, advantages, and objects of the invention will become apparent from the specification and drawings.